Template-Free Hydrothermal Growth of Nickel Sulfide Nanorods as High-Performance Electroactive Materials for Oxygen Evolution Reaction and Supercapacitors

Abstract

Transition-metal sulfides with nanostructured features grown on a conductive substrate have been suggested as a promising alternative to precious metal-based electrocatalysts for energy conversion and storage. Here, we configure the facile and single-step growth of nickel sulfide nanorods on Ni mesh (NiS/Ni) via a template-free hydrothermal approach for the oxygen evolution reaction (OER) and supercapacitor applications. The surface morphology of NiS was strongly affected by changing the concentration of Ni and S precursors. X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDX) revealed the presence of NiS in the samples. Under optimized conditions, the NiS/Ni electrode displayed superior OER performance, demanding 330 mV overpotential to oxidize water at a current density of 10 mA cm–2 in 1.0 M KOH, with a Tafel slope of 67 mV dec–1. The material also demonstrated excellent charge storage capabilities, including specific capacitances of 1097 and 869 F g–1 at current densities of 2 and 20 mA cm–2, respectively. Moreover, the fabricated NiS/Ni exhibited appreciable energy and power densities (484 W h kg–1; 0.79 W kg–1). The superior OER performance and energy storage properties can be attributed to the large electrode/electrolyte interfacial area of the NiS/Ni electrode owing to the desirable nanorod-like surface morphology. This study thus presents a simple synthesis route for the preparation of highly active NiS/Ni as a potential electrode material for electrochemical energy conversion and storage devices.